The present invention relates to the holding of a rod in a rolling mill and for guiding rolled stock in the rolling mill for the rolling of tubes, and more particularly the invention relates to a device arranged between a rolling mill stand and the mandrel rod thrust mount, for holding such rods and being comprised of a stationary frame arranged along the rolling axis and on three sides thereof, but at a certain distance therefrom. Such a device is to have levers arranged transversely to the axis of rolling, which levers each have a guide element and are interconnected through suitable linkage for connection to a common drive for simultaneous pivoting. Moreover, such a device should include adjustable stops so as to adjust the pivot stroke of the levers in relation to different diameters as defined by the guide elements on the levers.
Devices for holding mandrel rods in rolling mills of the type referred to above are generally known, and they include, as stated, three levers with guide elements in a frame-like arrangement, Moreover, several such devices are arranged between the mandrel rod thrust mount and a mill stand proper. The respective mandrel rod is delivered to and taken from the holding device, the latter rod carrying the rolled stock for removal transversely to the direction of extension of these rods, there being a single gap between the levers and the guide elements. It thus can be seen that an exchange of mandrel rods is by necessity a sequential operation. The old one has to be removed first before a new one can take its place. This sequential operation takes a relatively long time as compared with the period of time of rolling proper. Therefore, this mode of operation for exchanging mandrel rods is not a very advantageous one from a point of view efficiency. Another disadvantage of the state of the art is to be seen in the fact that the guide elements are not very accurately adjustable in relation to the diameter of the hollow that is being rolled. The reason for this is believed to result from the hydraulic positioning under utilization of a piston cylinder arrangement of these guide elements.
The above mentioned state of the art is generally represented by the German printed patent applications Nos. 2,032,533 and 2,840,773 or U.S. Pat. No. 3,101,015.